Just going out on a limb here. New to this forum, but not new in any way to 2-strokes.
It's been my belief for a while that the extra oil we commonly run in these HT's is not for the Piston/Rings, but more for the bearings (lower in particular). Is it possible that 100:1 - no matter how good the oil - just isn't enough for proper lubrication of these bearings?
I've also used Amsoil Sabre with great success, but at 50:1. Recently i've been using Poulan 2-cycle Synthetic at 40:1 (recommended) but added 1 oz. of MMO as well (good cleaning and upper lube).
Any way you go, 100:1 just seems like it's too thin for these China Girls.....